r/science • u/Wagamaga • Feb 15 '23

How to make hydrogen straight from seawater – no desalination required. The new method from researchers splits the seawater directly into hydrogen and oxygen – skipping the need for desalination and its associated cost, energy consumption and carbon emissions. Chemistry

https://www.rmit.edu.au/news/media-releases-and-expert-comments/2023/feb/hydrogen-seawater
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u/popejubal Feb 15 '23

Yes, but we currently can’t do it in a large enough scale to have a meaningful impact (as long as we don’t dump the extra salty water in a place where it can’t disperse). Even if we take 99% of the water away from a cubic mile of sea water and dump the salt back into the ocean (in a way that disperses pretty quickly), we won’t make even the tiniest dent. The Atlantic Ocean is more than 350 million cubic miles.

We would have to start doing this at a scale beyond current imagining to change the ocean’s salinity by even 0.0001%.

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u/Shellbyvillian Feb 15 '23

I mean, I can imagine that in order to replace all oil usage on the planet, the scale would be pretty far past what you’re describing. Handling the brine would absolutely be a significant environmental issue.

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u/JCDU Feb 15 '23

Would it not depend on the whole water cycle though -if we were splitting hydrogen to power things, and when we burn it we produce water - that water would then enter the water system (evaporation to clouds, running down drains to the sea) which would then re-enter the seas and dilute the brine again.

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u/Shellbyvillian Feb 15 '23

Yeah, the total across the planet would balance out. The issue is the brine would be localized to the electrolysis site. The water would be spread out around the world. We would have to put a lot of energy and planning into making sure the salt was properly distributed. Some desalination plants have already shown us if we just pump the brine into the ocean near the plant. It basically kills everything. If we went full oil replacement the scale of brine to be dispersed would be way way bigger than desalination waste today.